1. Field
Disclosed herein is a contact-force sensor package, which contacts a human body and senses a sphygmus wave so as to measure blood pressure. Disclosed herein too is a method of fabricating the contact-force sensor package.
2. Description of the Related Art
With the increase in people's awareness and concern about health, various methods of measuring blood pressure have been developed. Among methods of measuring blood pressure, a Korotkoff sounds method, an oscillometric method, and a tonometric method are often used. The Korotkoff sounds method is a traditional method of measuring blood pressure. According to the Korotkoff sounds method, when sufficient pressure is applied to a body part through which arterial blood flows, blood flow is blocked and then as the pressure applied to the body part is reduced, the pressure at which a pulse sound is first heard is measured as the systolic pressure, and the pressure at which the pulse sound disappears is measured as the diastolic pressure.
The oscillometric method and the tonometric method are applied to a digitized apparatus for measuring blood pressure. The oscillometric method measures the systolic pressure and the diastolic pressure by detecting a pulse wave generated in a depressurization process that depressurizes a body part at a constant speed. The detection of the pulse wave is conducted after sufficiently pressurizing the body part through which arterial blood flows so as to block arterial blood flow. This is similar to the Korotkoff sounds method. The oscillometric method may also be conducted in a pressurization process that pressurizes the body part at a constant speed. A pressure at which the amplitude of a pulse waveform is at a specific level may be measured as a function of the systolic pressure or the diastolic pressure, as compared with a pressure at which the amplitude of the pulse waveform is at a maximum. Alternatively, a pressure at which the amplitude of the pulse waveform varies greatly may be measured as a function of the systolic pressure or the diastolic pressure. During the depressurization process of the body part at a constant speed after the pressurization process, the systolic pressure is measured before the moment at which the amplitude of the pulse waveform is at the maximum, and the diastolic pressure is measured after the moment at which the amplitude of the pulse waveform is at the maximum. On the contrary, in the pressurization process of the body part at a constant speed, the systolic pressure is measured after the moment at which the amplitude of the pulse waveform is at the maximum, and the diastolic pressure is measured before the moment at which the amplitude of the pulse waveform is at the maximum.
According to the tonometric method, blood pressure can be measured continuously according to the magnitude and shape of the sphygmus wave that is generated when a predetermined pressure at which the blood flow in the artery is not completely blocked is applied to the body part.
In the tonometric method, a contact-force sensor package, which contacts the skin to sense vibration of the artery so as to measure blood pressure, is used. The contact-force sensor package may include a beam that vibrates due to the sphygmus wave. In order to measure distribution of pressure along the widthwise direction of the artery, the contact-force sensor package includes a plurality of beams arranged in a line. The plurality of beams are arranged in the widthwise direction of the beams.
In order to more accurately measure blood pressure, the contact-force sensor package should be disposed on the artery so that the widthwise direction of the beams is perpendicular to the lengthwise direction of the artery. However, during measurement, it is not easy to accurately align and place the contact-force sensor package on the skin. The contact-force sensor package is often placed on the skin in a state where relative alignment with respect to the artery is difficult to perform accurately. As such, the accuracy of measuring the blood pressure of a patient is reduced.